In the height of ski season this year, blades of grass and patches of dirt still dot cross country ski trails in Aspen, Colo. Conditions like this present a conundrum for professional skiers: Their livelihood relies on snow and cold temperatures, but essentials like travel and snow-making come with an environmental cost.

In the brave new world of synthetic biology, scientists can now brew up viruses from scratch using the tools of DNA technology.

The latest such feat, published last month, involves horsepox, a cousin of the feared virus that causes smallpox in people. Critics charge that making horsepox in the lab has endangered the public by basically revealing the recipe for how any lab could manufacture smallpox to use as a bioweapon.